Most of metropolitan area networks and enterprise networks are constructed by adopting a ring network. A technology adopted by the ring network is generally an RPR (Resilient Packet Ring, resilient packet ring) or an Ethernet ring. The RPR requires dedicated hardware, and therefore, its cost is relatively high and its application is relatively few; the Ethernet ring has a low cost and is widely applied.
As shown in FIG. 1, a general ring network includes a master node and transit nodes, and the master node includes an active port and a standby port. The working mechanism of the ring network is as follows: the active port of the master node periodically sends out a protocol packet, and the protocol packet is transmitted through the transit nodes on the ring network to the standby port of the master node; when the standby port can receive the protocol packet within specified time, the ring network is considered as complete; otherwise, it indicates that a fault exists in the ring network.
However, in the foregoing working mechanism, neither a network device as a master node nor a network device as a transit node supports topology discovery of the ring network, and then operations, such as accurate fault determination and blocked port designation, also cannot be performed on network devices on the ring network.